Sounds like its a warning for now (edit: I think that's implied by the switch from red to green), and maybe a degree of bragging when they're made for the publi

Sounds like its a warning for now (edit: I think that's implied by the switch from red to green), and maybe a degree of bragging when they're made for the public: “I felt using the infinity symbol was the best way to represent the ‘car of the future,’ ” said department Director Bruce Breslow. “The unique red plate will be easily recognized by the public and law enforcement and will be used only for licensed autonomous test vehicles. When there comes a time that vehicle manufactures market autonomous vehicles to the public, that infinity symbol will appear on a green license plate.” [1] I think there could be an element of marketing to it, too: Google labelled its self-driving cars to distinguish them from its StreetView cars, because people didn't notice the difference[2]. Moreover, they proudly label "Self-Driving Car" in big letters on their vehicles. [1] http://www.nevadanewsbureau.com/2012/05/07/nevada-dmv-issues-first-autonomous-vehicle-license-to-google/ http://www.nevadanewsbureau.com/2012/05/07/nevada-dmv-issues... [2] A Thrun Udacity lecture I think